In general, a hinge assembly used of a cellular telephone has a first and a second hinge member. The first and second hinge members are turnably connected to a transmission section and a reception section of the cellular telephone and are also connected to each other through a hinge pin. By this, the transmission section and reception section of the cellular telephone are turnably connected to each other.
The first and second hinge members are abutted against each other through bias means such as a coiled spring or the like. FIGS. 13(A) and 13(B) show abutment surfaces of the first and second hinge members 1, 2. The abutment surface of the first hinge member 1 has three fitting recesses 1a, 1b, 1c each having a generally trapezoidal configuration in section and arranged in predetermined positions in the circumferential direction. An abutment surface of the second hinge member 2 has two fitting projections 2a, 2b formed thereon. Those two fitting projections 2a, 2b are, when, for example, the transmission section and the reception section are turned to a closed position, fitted respectively into the fitting recesses 1a, 1b as shown in FIG. 13(C). Then, a biasing force of the bias means is converted into a force for turning the first and second hinge members 1, 2 by slant surfaces (force conversion mechanism) of the fitting recesses 1a, 1b and fitting projections 2a, 2b. This turning force causes the transmission section and the reception section to turn at a high speed and collide with each other vigorously. As a result, a click sound is generated. When the transmission section and the reception section are turned into an open position, the fitting projections 2a, 2b are fitted respectively into the fitting recesses 1c, 1a and the transmission section and the reception section are collided with each other. By this, a click sound is generated (see Japanese Patent Application Laid-Open No. H07-11831).
In the above-mentioned conventional hinge assembly, when the transmission section and the reception section are turned into the closed or open position, i.e., when the fitting projections 2a, 2b are fitted respectively into the fitting recesses 1a, 1b (1c, 1a), if the transmission section and the reception section are turned at a low speed against the biasing force of the bias means, the transmission section and the reception section are merely contacted with each other and they are never collided with each other vigorously. Thus, no click sound is generated.
The present applicant has proposed a hinge assembly capable of solving the above problem in Japanese Patent Application No. H11-376023. In that hinge assembly, a movable member is non-turnably but movably connected to a first hinge member and the movable member is abutted against a second hinge member by a coiled spring (bias means). Abutment surfaces of the movable member and the second hinge member have a fitting projection and a fitting recess formed thereon. A second hinge member and a reception section (or transmission section) are provided with an abutment projection and an abutment recess into which the abutment projection can be fitted. As the abutment projection is fitted into the abutment recess, the second hinge member turns following turning movement of the reception section. However, a width of the abutment recess in the circumferential direction is set slightly larger than a width of the abutment projection in the circumferential direction. Accordingly, the second hinge member can turn by a fine angle relative to the reception section.
In the hinge assembly thus constructed, when the reception section is turned into the closed position or open position and the fitting projection is fitted into the fitting recess, the second hinge member is caused to turn rapidly relative to the reception section by the biasing force of the bias means. As a result, a side surface of the abutment projection in the circumferential direction is abutted with a side surface of the abutment recess in the circumferential direction to thereby generate a click sound. In this case, the second hinge member, when the fitting projection is fitted into the fitting recess, is turned at a high speed relative to the reception section irrespective of the turning speed of the transmission section and reception section. Accordingly, even if the transmission section and reception section are turned at a low speed, a click sound can be generated.
However, in the hinge assembly of the above-mentioned patent application, it is necessary that the transmission section and reception section are provided with the abutment recess or abutment projection for generating a click sound. This gives rise to such a problem that it is unknown whether a click sound can actually be generated until the hinge assembly is attached to transmission section or reception section. Therefore, there is such a possibility that a click sound is not generated due to dimensional error or the like, or a click sound, if generated, is very small.